Ligament guide registration

ABSTRACT

A patient-specific guide tool for guiding an instrument toward a bone for implantation of a prosthetic device is disclosed. The guide tool includes a body portion having a guide element, and a patient-specific portion having at least one patient-specific mating feature that is configured to engage a soft tissue at or near the bone. A method of manufacturing a guide tool for guiding an instrument toward a bone is also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. Provisional Patent Application No. 61/893,570 filed on Oct. 21, 2013. The entire disclosure of the above application is incorporated herein by reference.

FIELD

The subject disclosure is related to various patient-specific alignment guides for use in joint replacement, resurfacing procedures and other procedures related to the joint or the various bones of the joint, including adjacent bones. A feature on the patient-specific alignment guides conforms to or engages a soft tissue to align a guide portion of the guides to a predetermined position relative to a bone at the joint. The soft tissue can be a ligament, tendon, muscle, fibrous tissue or fat. The patient-specific alignment guides are designed and constructed preoperatively based on two- or three-dimensional images of the patient's bone and soft tissue at or near a joint.

BACKGROUND

This section provides background information related to the present disclosure which is not necessarily prior art.

Joint reconstruction surgery requires careful planning by a surgeon and specialized instrumentation. Methods used for reconstructing a joint sometimes are not sufficiently accurate to reproduce the natural movement of the joint. Planning for the surgery is often based on two-dimensional x-ray films and surgeons often resort to shaping prosthetics during surgery. During the surgery, the surgeon typically uses non-patient specific alignment guides to prepare a defect on a bone for implantation of a prosthesis.

Recently, patient-specific alignment guides have been implemented as an alternative to standard orthopedic instrumentation and planning. The manufacture of patient-specific guides can require imaging protocols from which three-dimensional and pre-operative plans are created. These pre-operative plans can be used to create the patient-specific guides, which generally “lock” or “nest” into native boney landmarks at the site of the defect. When used in surgery, the patient-specific guide sits on a bone surface in order for the surgeon to carry out the pre-operatively planned procedure.

Although current patient-specific guides are an improvement from previous instrumentation, there remains a need for patient-specific instruments that reference landmarks other than bone.

SUMMARY

This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.

A patient-specific guide tool for guiding an instrument toward a bone for implantation of a prosthetic device is disclosed. The guide tool comprises a body portion that includes an engagement surface and a guide feature. The guide feature is configured to guide movement of the instrument toward the bone. The guide tool further comprises a patient-specific portion that is coupled to the body portion. The patient-specific portion includes at least one patient-specific attachment portion including at least one patient-specific soft tissue mating feature that is configured to conform to or engage a first soft tissue at or near the bone to thereby position the engagement surface at a predetermined position relative to the bone. The mating feature can be a hook, notch, slit, slot, or tab. The soft tissue can be a ligament, tendon, muscle, fibrous tissue, or fat.

A patient-specific guide tool for guiding an instrument toward a bone for implantation of a prosthetic device is also disclosed. The guide tool comprises a body portion and a first patient-specific portion extending from the body portion. The body portion can include a guide feature having an elongated bore. The guide feature is configured to guide movement of the instrument toward the bone. The first patient-specific portion includes at least one patient-specific mating feature that is configured to engage soft tissue at or near the bone in accordance with a two-dimensional or three-dimensional model of the bone and soft tissue of a specific patient reconstructed preoperatively from at least one image scan of the patient. The guide tool further comprises a second patient-specific portion extending form the body portion. The second patient-specific portion includes a patient-specific bone engaging surface. The guide tool thereby positions the guide feature at a predetermined position relative to the bone.

A method of manufacturing a guide tool for guiding an instrument to a bone is also disclosed. The method comprises obtaining at least one image of at least a portion of the bone; determining the location of soft tissue at or near the bone; generating a two-dimensional or three-dimensional model of the bone and soft tissue; and fabricating a patient-specific guide tool having a body portion and a patient-specific portion, the body portion including a guide feature, and the patient-specific portion including at least one mating feature that is configured to engage the soft tissue according to the two-dimensional or three-dimensional model. Determining the location of soft tissue at or near the bone can comprise obtaining an MRI, CT scan or ultrasound of the portion of the bone. Alternatively, determining the location of soft tissue at or near the bone can comprise obtaining an X-ray of the bone of the specific patient and locating the position of the soft tissue at or near the bone according to known locations of the soft tissue relative to the bone.

Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

FIG. 1 is a representation of a patient-specific acetabular guide;

FIG. 2 is a representation of a patient-specific acetabular guide on an acetabulum;

FIG. 3 is a representation of a patient-specific acetabular guide comprising a patient-specific rim portion on an acetabulum;

FIG. 4 is a a representation of a patient-specific acetabular guide comprising a patient-specific rim portion having a pair of guiding elements on an acetabulum;

FIG. 5 is a representation of a reamer aligned with a pilot hole in an acetabulum;

FIG. 6 is a representation of a pelvis having alignment pins positioned in the pelvis;

FIG. 7 is a representation of a patient-specific tibial guide positioned on a proximal end of a tibia;

FIG. 8 is a representation of a patient-specific tibial guide with alignment pins inserted through guide elements;

FIG. 9 is a representation of a proximal end of a tibia with alignment pins inserted in the anterior face of the tibia;

FIG. 10 is a representation of a tibial cut block positioned adjacent to an anterior face of a tibia; and

FIG. 11 is a representation of a trial plate positioned adjacent to a superior face of a resected tibia at a proximal end.

Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference to the accompanying drawings.

The present teachings generally provide patient-specific surgical instruments that include, for example, alignment guides, drill guides, templates, cutting/resection guides for use in joint replacement, resurfacing procedures and other procedures related to the joint or the various bones of the joint, including adjacent bones. A feature on the surgical instruments can be placed in contact with soft tissue to align a guide portion of the instrument to a face of a bone at the joint. The soft tissue can be a ligament, tendon, muscle, fibrous tissue or fat.

In various embodiments, the joint is a hip. In such embodiments, the present teachings generally provide a patient-specific acetabular guide or proximal femoral guide for use in orthopedic surgery, such as in joint replacement or revision surgery, for example. The patient-specific alignment guides can be used either with conventional or patient-specific implant components prepared with computer-assisted image methods.

In other embodiments, the joint is a knee. When the joint is a knee, the patient-specific surgical instruments can be used in knee joint replacement, resurfacing procedures and other procedures related to the knee joint or the various bones of the knee joint, including the femur and the tibia. The present teaching can be applied to partial and full knee reconstructions.

In a further embodiment, the joint is a shoulder. When the joint is a shoulder, the patient-specific surgical instruments can be used in shoulder joint replacement, resurfacing procedures and other procedures related to the shoulder joint or the various bones of the shoulder joint, including the glenoid and adjacent bones. The present teachings can be applied to anatomic shoulder replacement and reverse shoulder replacement.

The patient-specific instruments can be used either with conventional implant components or with patient-specific implant components and/or bone grafts that are prepared using computer-assisted image methods according to the present teachings. Computer modeling for obtaining two or three dimensional images of the patient's anatomy using MRI or CT, X-ray, or ultrasound scans of the patient's anatomy, the patient-specific prosthesis components and the patient-specific guides, templates and other instruments, can be designed using various CAD programs and/or software available, for example, by Materialise USA, of Plymouth, Mich.

The patient-specific instruments and any associated patient-specific implants and bone grafts can be generally designed and formed using computer modeling based on two or three dimensional anatomic image(s) generated from X-rays, MRI, CT, ultrasound or other medical scans. Specifically, an anatomical feature (e.g., a scapula, knee, or pelvis with surrounding soft tissue) can be imaged to detect certain features of the anatomy (e.g., dimensions, curvature of surfaces, soft tissues, etc.). Then, patient-specific instruments can be formed according to these measurements. Various pre-operative procedures are disclosed in commonly assigned U.S. Pat. No. 8,092,465, issued on Jan. 10, 2012, U.S. patent Publication No. 2011/0184419, published on Jul. 28, 2011, and U.S. Publication No. 2012/0310399, published on Dec. 6, 2012, which are all incorporated herein by reference in their entirety.

The patient-specific instrument can have a three-dimensional engagement feature that is complementary and made to conformingly contact or engage a soft tissue. In some embodiments, the patient-specific instrument can further have a three-dimensional engagement surface that is a mirror image or negative of a boney surface or cartilage. The three-dimensional engagement surface is complementary to and made to conformingly contact, engage, or nest on a bony anatomical surface or cartilage. Thus, the patient-specific instruments can be configured to fit at only one position to the anatomical surface. The patient-specific instruments can include custom-made guiding formations, such as, for example, guiding bores or cannulated guiding posts or cannulated guiding extensions or receptacles that can be used for supporting or guiding other objects, such as instruments, drill guides, reamers, cutters, cutting guides and cutting blocks or for inserting pins or other fasteners according to a surgeon-approved pre-operative plan.

In various embodiments, the patient-specific instruments can also include one or more patient-specific alignment guides for receiving and guiding a tool, such as a drill or pin or guide wire at corresponding patient-specific orientations relative to a selected anatomic axis for the specific patient. The patient-specific instruments can include guiding or orientation formations and features for guiding the implantation of patient-specific or off-the-shelf implants associated with the surgical procedure. The geometry, shape and orientation of the various features of the patient-specific instruments, as well as various patient-specific implants and bone grafts, if used, can be determined during the pre-operative planning stage of the procedure in connection with the computer-assisted modeling of the patient's anatomy. During the pre-operative planning stage, patient-specific instruments, custom, semi-custom or non-custom implants and other non-custom tools, can be selected and the patient-specific components can be manufactured for a specific-patient with input from a surgeon or other professional associated with the surgical procedure.

In the following discussion, the terms “patient-specific”, “custom-made” or “customized” are defined to apply to components, including tools, implants, portions or combinations thereof, which include certain geometric features, including surfaces, curves, or other lines, and which are made to closely conform as mirror-images or negatives or complementary surfaces of corresponding geometric features or anatomic landmarks of a patient's anatomy obtained or gathered during a pre-operative planning stage based on two or three dimensional computer images of the corresponding anatomy reconstructed from image scans of the patient by computer imaging or X-ray methods. Further, patient-specific guiding features, such as, guiding apertures, guiding slots, guiding members or other holes, openings, or guide surfaces that are included in alignment guides, drill guides, cutting guides, rasps or other instruments or in implants are defined as features that are made to have positions, orientations, dimensions, shapes and/or define cutting planes and axes specific to the particular patient's anatomy including various anatomic or mechanical axes based on the computer-assisted pre-operative plan associated with the patient.

The prepared patient-specific alignment guides can be configured to mate in alignment with natural soft tissue landmarks by orienting and placing the corresponding alignment guide intra-operatively at or near the bone to mate with corresponding soft tissue. In some embodiments, the patient-specific alignment guides can further be configured to mate in alignment with natural boney anatomic landmarks by orienting and placing the corresponding alignment guide intra-operatively on top of the bone to mate with corresponding boney landmarks, as well as with soft tissue landmarks. The soft tissue and boney landmarks function as passive fiducial identifiers or fiducial markers for positioning of the various alignment guides, drill guides or other patient-specific instruments.

The various patient-specific alignment guides can be made of any biocompatible material, including, polymer, ceramic, metal or combinations thereof. The patient-specific alignment guides can be opaque, semi-transparent, or transparent. The patient-specific alignment guides can be disposable and can be combined or used with reusable and non patient-specific cutting and guiding components.

More specifically, the present teachings provide various embodiments of patient-specific acetabular, knee, glenoid, or other appropriate guides. The acetabular, knee, glenoid or other appropriate guides of the present teachings can have patient-specific engagement surfaces that reference various portions of the hip, knee, or shoulder joint and include drill guides, guiding bores or sleeves or other guiding formations that can accurately position a guide wire for later acetabular, knee, or glenoid preparation and implantation procedures and for alignment purposes, including implant position control, implant version control, implant inclination control.

In the following, when of portion of a patient-specific guide is described as “referencing” a portion of the anatomy, it will be understood that the referencing portion of the patient-specific guide is a patient-specific portion or surface mirroring or negative to the corresponding referenced soft tissue, cartilage surface and/or bone surface. Exemplary, non-limiting patient-specific guides are shown, but additional patient-specific guides can be configured based on the present teachings.

With reference to FIGS. 1-4, the present teachings provide various exemplary patient-specific acetabular guides 100, 200, 300. The acetabular guides 100, 200, 300 can be used in connection with various other instruments to facilitate guided reaming of an acetabulum 20 of a pelvis 22 of a specific patient and guided insertion and implantation of an acetabular implant or acetabular cup in the acetabulum 20. The patient-specific acetabular guides 100, 200, 300 engage the acetabulum 20 of the specific patient in only one position and can provide an accurate alignment axis relative to a planned orientation of an acetabular cup. The acetabular guides 100, 200, 300 can also provide secure fitting and rotational stability in a design that is lightweight with minimal size and bulk.

FIG. 1 illustrates a patient-specific acetabular guide 100, having a patient-specific soft tissue mating feature 102, a patient-specific body 104 with a bone engaging surface 105 and an opposing surface 107, and a guiding or pilot element 106 having an elongated bore 108 with a patient-specific alignment axis A. The soft tissue mating feature 102 can comprise two substantially parallel plates 112, 114 coupled together at a stop 116 in a U-shape defining a slot 118. The mating feature 102 is configured to conform, nest, receive, or engage a soft tissue. While a single soft tissue mating feature 102 is illustrated, it should be understood that multiple soft tissue mating features can be integrated into a single guide and engage multiple distinct soft tissue areas to provide added stability. In some embodiments, the bone engaging surface 105 is negative or mirror image of the surface of the acetabulum 20. When positioned on the acetabulum 20, the bone engaging surface 105 nests on the boney surface. In other embodiments, the bone engaging surface 105 does not mirror, or only slightly mirrors the surface of the acetabulum. In such embodiments, the acetabular guide 100 is positioned only by the soft tissue mating feature 102.

In FIG. 2, the patient-specific acetabular guide 100 is positioned on the acetabulum 20 of the pelvis 22 with the soft tissue mating feature 102 mating or engaging with a transverse acetabular ligament 80. The mating feature 102 can mate or engage with the transverse acetabular ligament 80 in such a manner that the ligament 80 contacts the parallel plates 112, 114 and the stop 116, which define the slot 118. The mating feature 102 is configured to conform, nest, or engage a soft tissue. The alignment axis A is configured to be central to the acetabulum 20 and perpendicular to the acetabulum's surface when the guide 100 is positioned on the acetabulum 21. As mentioned above, the bone engaging surface 105 may or may not be a negative or mirror image of the surface of the acetabulum 20.

The acetabular guide 100 can be provided in various fitment options depending on the planned exposure of the acetabulum 20 for the reaming procedure and implantation. Each fitment option can include a portion that mates with the transverse acetabular ligament 80, which provides a landmark for rotational stability and unique positioning on the acetabulum 20. To additionally improve stability, each fitment option can also include a portion that covers the acetabular fossa at the center of the acetabulum 20. As shown in FIGS. 3 and 4, another fitment option for the acetabular guide includes a rim portion 210, 310 that is complementary to a portion of an acetabular rim 24. The rim portion 210, 310 can have a concave surface that references and mates with a convex acetabular rim 24, thus providing additional stability to guides 200, 300. The rim portion 210, 310 can be a mirror image or negative of the rim surface 24, enabling the rim portion 210, 310 to nest, engage, or conform to the rim 24. Each fitment option allows the acetabular guide 100, 200, 300 to have a compact size, extend through the center of the acetabulum 20 for alignment, and include portions that can fit over various anatomic landmarks in a unique position for the patient. The particular fitment option can be selected for each specific patient based on the patient's anatomy, the procedure to be performed and the surgeon's preference and/or technique.

Referring to FIGS. 1-2, the patient-specific soft tissue mating portion 102 of the acetabular guide 100 includes a feature that is functional to reversibly mate with soft tissue, such as a ligament. The feature can be a hook, notch, slit, slot, or tab. As shown in detail in FIG. 1, the mating feature 102 can include a slot 118 formed by two parallel plates 112, 114 and a stop 116 in a U-shape. The mating feature 102 is designed by using a two-dimensional or three-dimensional image or model of the acetabulum 20, surrounding soft tissue, and surrounding pelvic area of the specific patient, as described above. To avoid costly digital imaging protocols, the mating feature 102 can be designed by only an X-ray along with knowledge of the typical location of the transacetabular ligament or other soft tissue landmarks. Mating the acetabular guide 100 to the transverse acetabular ligament 80 enables the acetabular guide 100 to be oriented in a unique position within the acetabulum 20. The acetabular guide 100 can be designed to have a generally small thickness, such that it can form a lightweight three-dimensional shell from which the guiding element 106 extends opposite to the acetabular surface. The guiding element 106 can be formed to be a monolithic or integral portion of the acetabular guide 100. Alternatively, the guiding element 106 can be modularly and removably coupled to the acetabular guide 100, using, for example, a threaded connection, snap-on connectors, or other removable attachments.

FIG. 3 shows a patient-specific acetabular guide 200 with an additional fitment option. The guide 200 includes a patient-specific soft tissue mating feature 202, a patient-specific body 204 with a bone engaging surface 205 and an opposing surface 207, and a guiding or pilot element 206 having an elongated bore 208. As illustrated, the acetabular guide 200 is generally similar to guide 100. Unlike acetabular guide 100, acetabular guide 200 further comprises a patient-specific rim portion 210 that is complementary to a portion of the acetabular rim 24. In some embodiments, a concave surface of the rim portion 210 mates with the convex rim 24. Acetabular guide 200 has a patient-specific soft tissue mating feature 202, patient-specific body 204, and a patient-specific rim portion, which collectively impart greater stability to the guide 200 when it is positioned on an acetabulum 20. In various embodiments, the bone engaging surface 205 of the body 204 is a mirror image or negative of the surface of the acetabulum 20, which allows the guide 200 to nest on the articular surface of the acetabulum 20 to provide further stability.

FIG. 4. shows a patient-specific acetabular guide 300, similar to acetabular guide 200. Acetabular guide 300 comprises a soft tissue mating feature 302, a patient-specific body 304 with a bone engaging surface 305 and an opposing surface 307, a guiding or pilot element 306 having an elongated bore 308, and a patient-specific rim portion 310. In various embodiments, the bone engaging surface 305 of the body 203 is a mirror age or negative of the surface of the acetabulum 20, which allows the guide 300 to nest on the boney surface to provide further stability. Acetabular guide 300 further includes a second guiding or pilot element 312 having an elongated bore 314, and a third guiding or pilot element 316 having an elongated bore 318. The guiding elements 312, 316 can be formed to be a monolithic or integral portion of acetabular guide 300. Alternatively, the guiding elements 312, 316 can be modularly and removably coupled to the acetabular guide 300, using, for example, a threaded connection, snap-on connectors, or other removable attachments. The guiding elements 312, 316 are located at predetermined locations relative to the acetabulum 20. A surgeon can drill guide holes and/or insert guide pins through the guiding elements 312, 316 and into the pelvis 22.

FIG. 5 shows a pelvis 22 and acetabulum 20 including a pilot hole 330 in the acetabulum 20, and pilot holes 332, 334 in the pelvis 22, near the acetabular rim 24. The pilot hole 330 could be made by drilling through guiding elements 106, 206, 306 of patient-specific acetabular guides 100, 200, 300 shown in FIGS. 1-3. Pilot hole 330 can be used to guide an instrument, such as a reamer 336 having a protruding guide feature 338. The reamer can be properly aligned with the acetabulum 20 by inserting the protruding guide feature 338 of the reamer 336 into pilot hole 330.

As shown in FIG. 6, alignment pins 340, 342 can be drilled into the pelvis 22 by guiding them through guiding elements 312, 316 of the patient-specific acetabular guide 300 shown in FIG. 4. A secondary guide 350 can be guided down the alignment pins 340, 342 after guide 300 is removed. The secondary acetabular guide 350 can include a reaming alignment pin inserted into a cannulated feature 352 on the secondary guide 350 having a bore 354. The reaming alignment pin can be used to further align a reamer, such as the reamer 336 of FIG. 5, to ensure the reamer 336 is centered relative to the acetabulum 20, and to ensure the reaming is performed at a correct angle and orientation in relation to the acetabulum 20 and the pelvis 22. In various embodiments, the alignment pin can be coupled to the reamer 336 as a further aid to orient it in a desired position. Additional embodiments and a more detailed discussion on the use of the guide bores and pins can be found in U.S. Patent Publication No. 2012/0226283, published Sep. 6, 2012, which is incorporated herein by reference.

With reference to FIG. 7, the present teachings further provide various exemplary patient-specific tibial guides, such as patient-specific tibial guide 400. The tibia guide 400 can be used in connection with various other instruments to facilitate guided resecting of a proximal end of a tibia of a specific patient and guided insertion and implantation of a tibial implant. The patient-specific tibial guides 400 engage the proximal tibia of the specific patient in only one position. The tibial guides 400 can also provide secure fitting and rotational stability.

FIG. 7 illustrates the patient-specific tibial guide 400, having a first patient-specific soft tissue mating feature 402, a second patient-specific soft tissue mating feature 404, and optionally a third patient-specific soft tissue mating feature 406. The tibial guide 400 also comprises a patient-specific body 408 with a first surface 409 that contacts an anterior surface of a tibia 410 and a second surface 411 that contacts a superior surface of a tibia 412, anterior guiding or pilot elements 414, 416 having elongated bores 418, 420 positioned on the anterior surface 409, and superior guiding or pilot elements 422, 424 having elongated bores 426, 428 positioned on the superior surface 411. The soft tissue mating features 402, 404, 406 comprise substantially parallel surfaces 409, 411 that are coupled at a stop 413, thereby forming a U-shaped slot 415. The position of the soft tissue mating features 402, 404, 406 can be predetermined by referencing three dimensional CT or MRI scans, or by referencing two-dimensional X-rays and light of typical ligament locations in a knee. The patient-specific tibial guide 400 is positioned on a proximal end 90 of a tibia 92 with the first soft tissue mating feature 402 mating with a medial collateral ligament (MCL) 94, the second soft tissue mating feature 404 mating with an anterior cruciate ligament (ACL) 96, and the optional third soft tissue mating feature 406 mating with a lateral collateral ligament (LCL) 98 by positioning the mating features 402, 404, 406 to receive the respective ligaments 94, 96, 98 in the U-shaped slots 415. In general, the mating features 402, 404, 406 are configured to conform, receive, nest, or engage soft tissue.

The tibial guide 400 can be provided in various fitment options depending on the desired stability of the tibial guide 400 on the tibia 92. Each fitment option can include a portion that mates with the ACL 96, which provides a landmark for rotational stability and unique positioning on the tibia 92. To additionally improve stability, each fitment option can also include a portion that mates with the MCL 94. To additionally improve stability, each fitment option can also include a portion that mates with the LCL 98. Additionally, the patient-specific body 408 of the tibial guide 400 can comprise a bone engaging surface 413 that is a negative or mirror image of boney and/or articular landmarks in the tibia 92. Accordingly, the body 408 of the tibial guide 400 can nest on the tibia to impart greater stability. Each fitment option allows the tibial guide 400 to have a compact size, and include portions that can fit over various anatomic landmarks in a unique position for the patient. The particular fitment option can be selected for each specific patient based on the patient's anatomy, the procedure to be performed and the surgeon's preference and/or technique.

The patient-specific soft tissue mating portions 402, 404 (406) of the tibial guide 400 include a feature that is functional to reversibly mate with soft tissue, such as a ligament. The feature can be a hook, notch, slit, slot, or tab. As shown in detail in FIG. 7, the mating features 402, 404, 406 can be slots 415 defined by two substantially parallel surfaces 409, 411 and a stop 413 that form a U-shape. The mating features 402, 404, 406 are designed by using a two-dimensional X-ray of the tibia 92 or by using a three-dimensional image or model of the tibia 92, and surrounding soft tissues of the specific patient generated by CT or MRI scans. Mating the tibial guide 400 to the ACL 96, MCL 94, and optionally to the LCL 98 enables the tibial guide 400 to be oriented in a unique position on the proximal end 90 of the tibia 92. The tibial guide 400 can be designed to have a generally small thickness, such that it can form a lightweight three-dimensional shell from which the guiding elements 414, 416, 422, 424 extend opposite to the anterior and superior faces 410, 412 of the tibia 62. The guiding elements 414, 416, 422, 424 can be formed to be monolithic or integral portions of the tibial guide 400. Alternatively, the guiding elements 414, 416, 422, 424 can be modularly and removably coupled to the tibial guide 400, using, for example, a threaded connection, snap-on connectors, or other removable attachments.

FIG. 8 is a representation of the patient-specific tibial guide 400 positioned on a tibia 92 at the proximal end 90. Anterior alignment pins 440, 442 are drilled through a drill guide 444, through the anterior guiding or pilot elements 414, 416, and into the tibia 92. Likewise, superior alignment pins 446, 448 are drilled through a drill guide 450, through the superior guiding or pilot elements 422. 424, and into the superior face 412 of the tibia 92. Because the locations of the guiding or pilot elements 414, 416, 422, 424 are predetermined during the preoperational planning stage, they can be used to guide instruments to exact locations relative to the tibia 92.

FIG. 9 is a representation of the tibia 92 with the patient-specific tibial guide 400 and superior alignment pins 446, 448 removed. Pilot holes 452, 454 remain where the superior alignment pins 446, 448 were removed. The anterior alignment pins 440,442 remain inserted in the anterior face 410 of the tibia 92. As shown in FIG. 10, a tibial cut block 460 can be positioned adjacent to the anterior surface 410 of the tibia 92 by positioning the cut block 460 along the anterior alignment pins 440, 442. A resecting tool 462 can then be inserted through a guide slit 464 in the cut block 460 for resecting the proximal end 90 of the tibia 92 at a predetermined location.

FIG. 11 shows the tibia 92 with the superior alignment pins 446, 448 reinserted into the pilot holes 452, 454 shown in FIG. 8. The anterior alignment pins 440, 442 have been removed. A trial plate 470 is placed adjacent to a resected superior face 412′ of the tibia 92 by positioning the trial plate 470 along the superior alignment pins 440, 442. An alignment instrument 472 comprising a handle with an aperture 474 is placed along the superior alignment pins 440, 442, and adjacent to the trial plate 470. An alignment rod 476 is inserted through the aperture 474, which can be visualized with reference to the tibia 92 to ensure proper alignment. The alignment instrument 472, trial plate 470, and superior alignment pins 446, 448 can then be removed, and a tibial implant implanted adjacent to the superior face 412′ of the tibia 92. Additional embodiments and a more detailed discussion on the use of the guide bores and pins can be found in U.S. Patent Publication No. 20120316564, published on Dec. 13, 2012, which is incorporated herein by reference.

The present teachings also provide a method of manufacturing a guide tool for guiding an instrument to a bone. The method comprises obtaining at least one image of at least a portion of the bone and optionally of a soft tissue at or near the bone; and generating a two-dimensional or three-dimensional model of the bone and soft tissue. The image can be a MRI or CT scan, ultrasound or X-ray. Three-dimensional models can be generated from MRI and CT scans, which include boney and soft tissue structures. X-ray images can also be used to generate a model of bone. The approximate location of ligaments at or near the bone can be determined based on the location of ligaments in a typical patient. The bone can be any bone in the human body. The soft tissue can be a ligament, tendon, muscle, fibrous tissue or fat. The method further comprises fabricating a patient-specific guide tool having a body portion and a patient-specific portion. The body portion includes a guide feature, and the patient-specific portion includes at least one mating feature that is configured to conform to or engage the soft tissue according to the two-dimensional or three-dimensional model. Fabricating can be performed by any method known in the art.

The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure. 

What is claimed is:
 1. A patient-specific tibial guide for guiding an instrument toward a bone, the patient-specific tibial guide comprising: a patient-specific body comprising: a first surface configured to contact an anterior surface of a tibia of a patient; and a second surface configured to contact a superior surface of the tibia; a first mating feature extending from the body in a first patient-specific location and configured to engage a medial collateral ligament of the patient; and a second mating feature extending from the body in a second patient-specific location spaced from the first patient-specific location, the second mating feature configured to engage an anterior cruciate ligament of the patient.
 2. The patient-specific tibial guide according to claim 1, comprising: a third mating feature extending from the body in a third patient-specific location spaced from the first patient-specific location and the second patient-specific location, the third mating feature configured to engage a third soft tissue of the patient.
 3. The patient-specific tibial guide according to claim 2, wherein: the third soft tissue is a lateral collateral ligament of the patient.
 4. The patient-specific tibial guide according to claim 1, wherein: the first patient-specific location of the first mating feature and the second patient-specific location of the second mating feature are predetermined by referencing one or more of a three-dimensional CT scan, a three-dimensional MRI scan, and a two-dimensional X-ray.
 5. The patient-specific tibial guide according to claim 1, comprising: an anterior pilot element positioned on an anterior surface of the body, the anterior pilot element including an anterior pilot bore extending therethrough and configured to guide an alignment pin to a predetermined location of the anterior surface of the tibia of the patient.
 6. The patient-specific tibial guide according to claim 5 comprising: a superior pilot element positioned on a superior surface of the body, the superior pilot element including a superior pilot bore extending therethrough and configured to guide a second alignment pin to a second predetermined location of the superior surface of the tibia of the patient.
 7. The patient-specific tibial guide according to claim 6, wherein: the first mating feature comprises a pair of substantially parallel surfaces coupled at a stop, the pair of substantially parallel surfaces together with the stop forming a slot configured to receive the medial collateral ligament of the patient.
 8. The patient-specific tibial guide according to claim 1, wherein: the body comprises a bone engaging surface that is a negative of boney landmarks of the tibia of the patient, the bone engaging surface including the first surface and the second surface and configured to contact the honey landmarks of the tibia to position the tibial guide to be oriented on a predetermined location on a proximal end of the tibia.
 9. The patient-specific tibial guide according to claim 1, wherein engagement between the body and the anterior and superior surfaces of the tibia, engagement between the first mating feature and the medial collateral ligament, and engagement between the second mating feature and the anterior cruciate ligament are is configured to position the tibial guide to be oriented on a predetermined location on a proximal end of the tibia.
 10. A patient-specific tibial guide for guiding an instrument toward a bone, the patient-specific tibial guide comprising: a patient-specific body comprising: a first surface configured to contact an anterior surface of a tibia of a patient; and a second surface configured to contact a superior surface of the tibia; a first mating feature extending from the body in a first patient-specific location and configured to engage a medial collateral ligament of the patient; a second mating feature extending from the body in a second patient-specific location spaced from the first patient-specific location, the second mating feature configured to engage an anterior cruciate ligament of the patient; and a third mating feature extending from the body in a third patient-specific location spaced from the first patient-specific location and the second patient-specific location, the third mating feature configured to engage a lateral collateral ligament of the patient; wherein engagement between the body and the anterior and superior surfaces of the tibia, engagement between the first mating feature and the medial collateral ligament, engagement between the second mating feature and the anterior cruciate ligament, and engagement between the third mating feature and the lateral collateral ligament are configured to position the tibial guide to be oriented on a predetermined location on a proximal end of the tibia.
 11. The patient-specific tibial guide according to claim 10, wherein: the first patient-specific location of the first mating feature, the second patient-specific location of the second mating feature, and the third patient-specific location of the third mating feature are predetermined by referencing one or more of a three-dimensional CT scan, a three-dimensional MRI scan, and a two-dimensional X-ray.
 12. The patient-specific tibial guide according to claim 10, comprising: first and second anterior pilot elements positioned on an anterior surface of the body, the first and second anterior pilot elements each including an anterior pilot bore extending through the respective first and second anterior pilot elements, each anterior pilot bore configured to guide an alignment pin to a predetermined location of the anterior surface of the tibia of the patient.
 13. The patient-specific tibial guide according to claim 12, comprising: first and second superior pilot elements positioned on a superior surface of the body, the first and second superior pilot elements each including a superior pilot bore extending through the respective first and second superior pilot elements, each superior pilot bore configured to guide an alignment pin to a predetermined location of the superior surface of the tibia of the patient.
 14. The patient-specific tibial guide according to claim 13, wherein: the first mating feature comprises a pair of substantially parallel surfaces coupled at a stop, the pair of substantially parallel surfaces together with the stop forming a slot configured to receive the medial collateral ligament of the patient.
 15. The patient-specific tibial guide according to claim 10, wherein: the body comprises a bone engaging surface that is a negative of honey landmarks of the tibia of the patient, the bone engaging surface including the first surface and the second surface and configured to contact the honey, landmarks of the tibia to position the tibial guide to be oriented on a predetermined location on a proximal end of the tibia.
 16. A method of guiding an instrument to a tibia using a patient-specific tibial guide, the method comprising: contacting an anterior surface of a tibia of a patient with a first surface of a patient-specific body of a patient-specific tibial guide; contacting a superior surface of the tibia with a second surface of the patient-specific body; engaging, with a first mating feature that extends from the body, a medial collateral ligament of the patient in a first patient-specific location of the patient; and engaging, with a second mating feature that extends from the body, an anterior cruciate ligament of the patient in a second patient-specific location of the patient spaced from the first patient-specific location.
 17. The method according to claim 16, comprising: engaging, with a third mating feature that extends from the body, a third soft tissue of the patient in a third patient-specific location spaced from the first patient-specific location and the second patient-specific location.
 18. The method according to claim 17, wherein: the third soft tissue is a lateral collateral ligament. 